The UN nuclear watchdog IAEA has condemned Iran for being in breach of its non-proliferation obligations for the first time in almost two decades, diplomatic sources have said.

The agency's 35-nation board of governors passed a resolution to that effect on Thursday, they said.

They said the motion, drafted by the United States, Britain, France and Germany, was carried by 19 votes in favor. Russia, China and Burkina Faso opposed the motion, 11 abstained and two nations of the 35 did not vote.

Iran responded defiantly to the resolution by announcing it would open a new enrichment site and upgrade centrifuges at the Fordow nuclear facility.  

"The Islamic Republic of Iran has no choice but to respond to this political resolution," the Iranian Foreign Ministry and the Atomic Energy Organization of Iran said in a joint statement.

Restored UN sanctions on Tehran possible

The IAEA board "Finds that Iran's many failures to uphold its obligations since 2019 to provide the Agency with full and timely cooperation regarding undeclared nuclear material and activities at multiple undeclared locations in Iran ... constitutes non-compliance with its obligations under its Safeguards Agreement with the Agency," the resolution text, seen by Reuters news agency, said.

Thursday's move could lead to further tensions between the West and Iran over its nuclear program and pave the way for United Nations sanctions on Tehran to be restored later this year.

Undeclared nuclear materials

The resolution by the IAEA comes after Iran failed to give the agency credible explanations for the presence of uranium traces at undeclared sites in the country.

The report by the agency at the end of May found that three of the four locations "were part of an undeclared structured nuclear program carried out by Iran until the early 2000s and that some activities used undeclared nuclear material."

US intelligence services and the IAEA have suspected for some time that Iran had a secret nuclear weapons program it halted in 2003.

Iran has gradually been abandoning the commitments it made under the nuclear deal it agreed with world powers in 2015.

That deal, which collapsed after the US withdrew from it in 2018 during US President Donald Trump's first term, lifted some sanctions in exchange for restrictions on Tehran's nuclear program.

Growing Middle East tensions

The IAEA resolution comes as tensions in the region have been rising.

The US State Department announced on Wednesday that it was pulling out people whom it considered non-essential to its operations in the Middle East.

Staff reductions are being carried out at the US Embassy, and there are reports that personnel are also being moved from Kuwait and Bahrain over security concerns

President Donald Trump has also warned that Israel or the US could carry out airstrikes on Iranian nuclear facilities if ongoing US-Iran negotiations failed.

Iran in its turn has responded with threats to hit US bases in the region if the US takes military action.

Israel, Iran's regional archenemy, has meanwhile said the world must respond "decisively" to Iran's non-compliance with its nuclear obligations.

Edited by: Alex Berry